The electron transfer fromQA to QB in photosynthetic reactioncenters provides a good reaction for the study of the coupling of electron and proton transfer. Since the same species of quinone is found in both sites, the traditional methods for monitoring the reaction rely on Stark shifts in the spectra of nearby chromophores. However, Stark shifts cannot distinguish between electron and proton transfers. Replacement of the occupants of QA and QB with compounds with different semiquinone spectra allows direct monitoring of the electron transfer. We have characterized the electron transfer with these reaction centers. However, only 50% of the expected amplitude is seen, so part of the reaction occurs faster than our instrument response time (20 ms). This is unexpectedly fast and suggests that the older, indirect methods of measurement missed early time process. We would like to use the RLBL facilities to look for and the characterize these faster kinetic components.